Amateur Telescope Making & other do it yourself projects

ATM & other do it yourself projects

DIY Polar Scope Illuminator for EQ5 Mount

I recently bought a 2nd hand Sky-Watcher Explorer 200P on an EQ-5 mount off AstroBuySell UK.com and was pleased to discover that it came with a polar scope. For the unitiated, these are used for aligning the polar axis (that’s the extra one that alt-az mounts don’t have) to the north celestial pole so that objects can be tracked by moving the scope in the Right Ascension (RA) plane only. Alignment requires sighting Polaris through the polar scope so that it aligns with a specially engraved reticule inside the polar scope eyepiece. The problem is that when its dark, the reticule markings cannot be seen so have to artificially illuminated (but not too much otherwise it swamps the stars!)…by a polar scope illuminator. Of course, you can buy one at £23 but reviews of them were very mixed so I researched how to make one, after all it’s only a fancy dim torch how difficult can it be?

The description below is really a prototype (with help from utube) as I tried various options while making it. The bought ones fit on the eyepiece but mine fits on the inside the hole in the mount at the ‘objective’ end.

Parts Needed – plastic

From Screwfix, Wickes or Discount Store, Swadlincote

  • 32mm plastic equal tee with compression joints –– about £3.
  • 32mm socket plug – £1.20
  • 40mm socket plug – £1.20
  • 32mm PVC pipe – £2.40 for 3m – we need about 250mm! Try to find an off-cut.

Parts Needed – electrical

From RS Potts Babbington Lane, Derby

  • Small red LED
  • Small rocker switch
  • AA double battery holder
  • 1W rated resistor
  • Small connectors (3)
  • Low voltage cable
  • Insulating tape, or earth wire insulation
  • M4 screw, nut and washer
  • 2 x AA batteries

I had some of these already but I bought the LED, resistor and battery holder for a total of 94p.

Method – refer to photos

Cut the pipe into 2 pieces: 100mm for battery/switch compartment and 50mm for inserting into mount. The longer piece and the branch stub of the tee need to be cut to fit the rocker switch, making sure it faces downwards for easy access when looking through the polar scope. Cut away the flange of the 40mm plug to form a neat end for the battery compartment.

For my mount, I needed to reduce the diameter with a rasp/coarse emery for it to fit snugly inside the hole in the mount. This was a pain by hand but would take only minutes in a lathe.

I made a support (12mm x 150mm but length depends on your mount) for the wires to the LED from a 150mm length of pipe and bolted it to the bottom stub of the tee with M4 screw/nut. Tape wires to the support to keep them out of the field of view.

The 32mm plug is just a cap for the top plug when not in use. My photo shows the branch of the tee curving upwards but it’s better to arrange it curving downwards (remember mine is a prototype!).

Wire up the battery compartment, switch, resistor and LED (polarity is important for the LED). Carefully measure the lengths of wire needed to avoid excess. Soldering is better but I used small plastic connectors. Use tape or insulation to cover any bare wire connections.  Fit the batteries and test. If all ok, carefully thread the wired assembly into the tee piece and your ready to try it out. The support and position of the LED may need to adjusted/bent to avoid it shining directly into the polar scope.

You have a polar scope illuminator for about £10. At the next opportunity, I will attempt to take a photo of the view through the polar scope when illuminated and add to this post. Feel free to ask questions. To finish I would like to hear details from anyone who uses a 90 degree viewfinder on their polar scope, its a long way down to the eyepiece without one.

Illuminator Fitted to EQ5 Mount
Finished Assembly
Exploded View

Building a Shed/Observatory in 5 minutes

The one upside of the last few weeks abysmal lack of astro friendly weather is that I’ve finally had the opportunity to put together the time-lapse videos from my shed project. OK- It’s only 5 minutes with the help of time-lapse video- but it was quite a quick build when I actually got the chance to work on it.

One evening last May there was a unanimous perfect forecast from different weather apps and I dutifully set all the gear up for some imaging. Just as we were getting to darkness a thick bank of cloud rolled in. As it was not forecast, I decided to hang on for the sky to clear, and instead spent the next hour looking round the garden working out how I could have a more permanent set up with all of the advantages it gives. And no- the sky didn’t clear that night…

Looking about the internet there are some amazing creations- both home-made and purchased- but these were all well beyond my available resources for this project in either time or money. Besides keeping costs down, I wanted the following:

–          Really small footprint.

–          I didn’t want it to look like an observatory (which is much too grand a word anyway for this shed).

–          If I wanted to bring my mount out to a club evening or dark site, I didn’t want it to be any more hassle than taking the mount and scope out of the garage is.

So:

–          I used an 7’x5’ apex shed design. This has the disadvantage of limiting the view where the apexes are- but my views are restricted in those directions anyway- and with the smaller roof panels I can move them manually and drop them down the side walls.

–          Upside-down guttering is used to seal the gap at the top between the panels.

–          No pier- the tripod sits on bricks that come through the shed floor so I don’t cause vibrations when I’m walking around.

–          The roof panels slide off on fixed castors fitted to the shed walls (although in practice the tower bolts catch on the sides and it’s more of a lift than a slide).

–          The electrics are in a ventilated plastic storage box to keep them away from moisture. I run an outdoor cable from the garage when it’s in use. I’m using a Nevada power supply which has been a lot less hassle than using a battery, and I can’t prove it, but I think the mount is running better.

Overall, I’m pretty pleased with it- it only takes a couple of minutes to open the roof, the polar alignment seems to be pretty much spot on each time I check it (despite not having a pier) and my setup time to when I start the first sub has dropped from an hour to around twenty minutes or so. Most of this time is to align, frame and focus.

The shed came from Tiger Sheds and seems to be of reasonable quality. The weight of the roof panels was heavier than I had expected (when I was checking out the design I didn’t allow for the weight of the roof felt- blimey it’s heavy!!!) and I was thinking about ways to overcome this. But I’ve got used to the technique to move the panels, and it has stood up really well to some very wet and windy weather over the last few weeks. For now I’m inclined to leave it as it is. It’s also pretty snug in there. I never intended to use it for observing, but if I ever changed my mind about that I’d probably need to start again because space around the scope is pretty limited and alignment often involves a short stepladder and hanging off walls…

It will just about take a 1200mm Newt OTA, but with that one it is really cosy.

It isn’t quite finished yet- I’m in the process of adding some shelving, I need to improve the ventilation (I’m looking into solar powered fans, but failing that I’ll just put some vents in) and I need to lag the walls to help keep the temperature more stable.

So, if anyone is thinking about a more permanent setup, but is concerned about the cost and effort involved, it needn’t be an architectural masterpiece. The basic shed was £320 and with the materials for the base and other odds and sods I’m probably a little north of £500 for the whole project. Which will hopefully allow me to be a little more spontaneous with imaging. Or at least have wasted less time when ‘secret’ clouds come rolling in…

Hope you enjoy the video (speaking of which- this was partly put together with Videopad as recommended at a RAG meeting earlier in the year- I can second that recommendation! 😊).

Solargraphs – Summer>Winter Solstice 2018

All from Baked Bean cans within a 10 mile radius, using Ilford Multigrade B&W paper. Scanned and played with in Photoshop.

Andy’s first one, slightly different angle to his usual version.

And his second – massive amounts of water damage (was still a few mm of rain in the bottom of the can), but love the effect it’s created. This is his usual angle (so can be compared to previous attempts). Can just make out the house bottom right of centre and the tree to the left.

Mine, screwed to the house, SSE facing.

Sister’s from her new home. Was surprised at the very upper sun trace, but it can be matched to my own above. Thought at first it must have moved or have been a reflection from the inside top of the can. The cans are painted black inside and any movement would have created a double image of the houses – there isn’t anything to suggest that.

One I made up for a lady at my new workplace.

Damian

Dr Who Themed 60th Birthday Party!

Friday 28th Dec… a birthday invite from one of J’s friends.

Was thinking there could be plenty of ‘doctors’ present and considering the general age – probably the ‘Baker’ variety.

Couldn’t think of an easy to produce idea until the day before (and no access to large format printers anymore). On a walk I had a brainwave, so we took a detour to Tescos and purchased a pack (5 pairs) of ladies knee length tights for the grand sum of £2 ! Then stuffed them with tissue paper and held together with a couple of elastic bands.

All in-keeping with the good ole days of Dr Who monsters / Blue Peter card and sellotape!

Not forgetting something black to wear and a sigma graphic cut from a piece of silver card.

Add a ‘Moon desk light’ (watch battery powered), plus a USB extender cord, stuck together with a foam sticky pad for one prop, then a Christmas battery powered Christmas decoration – with addition of a cable tidy for the second prop…. and voila!

Ood do you think we are!

 

A hand-made K-9 made a surprise appearance also…

 

We were something of a hit with the kids!

Loved this – a Tardis, painted onto an (empty) Jack Daniel’s whisky bottle (plus Weeping Angel !)

The kids liked their (chocolate) rocket…

And we took a few bottles of some space themed drinks for the adults too…

Damian

Adding an on/off button to Ed’s battery pack

Today, I have added an on/off button to the battery pack Ed made for me. I have used a car/lorry 12V on/off button from Halfords, 25A cabling and connectors. This button goes between the 75AH leisure battery and inverter and is meant to avoid the situation where I accidently leave the inverter turned on draining the battery as happened to me recently. It took quite some time to get this working although for some reason I have not managed to get the 12V light to come on on the switch when it is turned on. More accurately, I did get that working too when the switch was not installed on the side of the case but it has not worked since I drilled the hole and screwed it on to the case!

The location of the switch below the plug sockets is to avoid the switch foulibg the handle of the case.

Andy

Andy

Adding anti-slip rubber sheet of Ed Mann’s battery pack

Ed Mann built a fantastic battery pack for several members of RAG including myself. These packs are based around a 75AH leisure battery and provide 12V and 230V outputs abd plenty of juice to power anything we need in the field from mounts to laptops.

However they are quite heavy. To help with transpirt i purchased a Homebase foldable sack truck.

There was still a problem left – the battery pack is housed in a plastic box that tends to slip on the sack truck and fall off. Bungy cords provided part of the solution and today I added the second aspect: I glued 3mm rubber sheet to the bottom of the battery pack and now it will never slip again! To acheive this, I had to empty the battery box first before I coukd turn the box over, but I got there eventually and aI am pleased with the result.

Andy

 

Modifying RELCO fluorescent starter to make homemade neon spectrometer calibration light part II (RECLO SC 480 S53993)

This follows on from my previous post on this subject.

Modifying RELCO fluorescent light starter to create neon calibration light for spectrometry

Today, I housed the new calibration light – I put four of the RELCO starter neon bulbs in the lid of a box – I attached them to a connection block inside the box.

In this way, I have four neon bulbs ready to use. I only connected one at a time. Each bulb has life span of 90 hiurs do when one burns out, moving the wires indide the box to the next bulb along allows the calibration light to continue to ne used.

As mentioned in the previous post, I have added a boc from ebay which will turn off the light after twenty minutes preserving the life of the bulbs when I inevitably forget to turn them off on the field!

The whole set up runs on 240V via an inverter on a leisure battery. I have ordered a RCD for safety and used boxes designed for external use and sealed all holes with a glue gun to minimize moisture ingress.

My first calibration spectrum taken using the above can be seen at this post, which follows on from the above:

First calibration spectra from RELCO neon starter bulb (RECLO SC 480 S53993) taken with Science Surplus DIY Spectrometer 9/9/2018

Andy